Electric toothbrush device and method

ABSTRACT

In one embodiment, the invention can be an electric toothbrush. The electric toothbrush may include a driving module configured to oscillate a brush unit; an acceleration sensor configured to generate an output signal; a signal extraction module configured to extract from the output signal (a) a first signal having a frequency at a first threshold or higher and (b) a second signal having a frequency at a second threshold or lower; a brushing site estimation module configured to estimate a brushing site of the brush unit based on the output signal of the acceleration sensor; and a correction module configured to correct the brushing site estimated by the brushing site estimation module based on an amplitude of the first signal and an amplitude of the second signal.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/735,414, filed Dec. 11, 2017, which claims priority under 35U.S.C. § 371 to PCT/US2016/036611, filed Jun. 9, 2016, which claimspriority under 35 U.S.C. § 119 to Japanese Patent Application No.2015-124172, filed Jun. 19, 2015, and Japanese Patent Application No.2015-122896, filed Jun. 18, 2015, the disclosures of which areincorporated herein by reference.

BACKGROUND

Electric toothbrushes are popular devices for cleaning teeth. Someelectric toothbrushes attempt to estimate the sites that the toothbrushhas brushed. This information can be useful in correcting bad brushinghabits and encouraging a more thorough brushing of all teeth. But suchtoothbrushes have difficulty providing accurate information. What isneeded is an electric toothbrush device that can accurately estimatebrushing sites.

BRIEF SUMMARY

The present disclosure is directed to an apparatus, method, and mediumfor estimating brushing sites. In one aspect, an electric toothbrushcomprises a trajectory detecting module configured to detect atrajectory of movement of a brush, the trajectory comprising a pluralityof positions; an attitude detecting module configured to detect anattitude of the brush; a site estimating module configured to estimate abrushing site for each of the plurality of positions of the trajectory,each estimated brushing site being based on the trajectory detected bythe trajectory detecting module; and a back most tooth detecting moduleconfigured to detect a back most tooth based on a change of the attitudedetected by the attitude detecting module; wherein the site estimatingmodule is further configured to correct the estimated brushing site foreach of the plurality of positions of the trajectory based on theestimated site of the detected back most tooth.

In another aspect, a method includes detecting a trajectory of movementof a brush, the trajectory comprising a plurality of positions;detecting an attitude of the brush; estimating a brushing site for eachof the plurality of positions of the trajectory, each estimated brushingsite being based on the trajectory detected; detecting a back most toothbased on a change of the attitude detected by the attitude detectingmodule; and correcting the estimated brushing site for each of theplurality of positions of the trajectory based on an estimated site ofthe detected back most tooth.

In another aspect, a non-transitory computer-readable storage mediumencoded with instructions which, when executed on a processor, performsa method of detecting a trajectory of movement of a brush, thetrajectory comprising a plurality of positions; detecting an attitude ofthe brush; estimating a brushing site for each of the plurality ofpositions of the trajectory, each estimated brushing site being based onthe trajectory detected; and detecting a back most tooth based on achange of the attitude detected by the attitude detecting module; andcorrecting the estimated brushing site for each of the plurality ofpositions of the trajectory based on an estimated site of the detectedback most tooth.

In yet another aspect, an electric toothbrush includes a driving moduleconfigured to oscillate a brush unit; an acceleration sensor configuredto generate an output signal; a signal extraction module configured toextract from the output signal (a) a first signal having a frequency ata first threshold or higher and (b) a second signal having a frequencyat a second threshold or lower; a brushing site estimation moduleconfigured to estimate a brushing site of the brush unit based on theoutput signal of the acceleration sensor; and a correction moduleconfigured to correct the brushing site estimated by the brushing siteestimation module based on an amplitude of the first signal and anamplitude of the second signal.

In another aspect, a brushing site estimation method for an electrictoothbrush includes extracting a first signal from an output signal ofan acceleration sensor of an electric toothbrush, the first signalhaving a frequency at a first threshold or higher; extracting a secondsignal from the output signal of the acceleration sensor, the secondsignal having a frequency at a second threshold or lower; estimating abrushing site of the brush unit based on the output signal of theacceleration sensor; and correcting the brushing site estimated by thebrushing site estimation module based on an amplitude of the firstsignal and an amplitude of the second signal.

In another aspect, a non-transitory computer-readable storage mediumencoded with instructions which, when executed on a processor, perform amethod of extracting a first signal from an output signal of anacceleration sensor of an electric toothbrush, the first signal having afrequency at a first threshold or higher; extracting a second signalfrom the output signal of the acceleration sensor, the second signalhaving a frequency at a second threshold or lower; estimating a brushingsite of the brush unit based on the output signal of the accelerationsensor; and correcting the brushing site estimated by the brushing siteestimation module based on an amplitude of the first signal and anamplitude of the second signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a block diagram illustrating an example configuration of anelectric toothbrush for describing an embodiment.

FIG. 2 is a perspective view illustrating an external appearance of theelectric toothbrush device of FIG. 1.

FIG. 3 is a cross section view illustrating an internal configuration ofthe electric toothbrush of FIG. 1.

FIG. 4 is a diagram illustrating the division of brushing sites.

FIG. 5 is a flow chart illustrating an example of the brushingevaluating process.

FIG. 6 is a diagram illustrating an example of the estimating method ofbrushing sites based on the attitude of the brush.

FIG. 7 is a diagram illustrating an example of the detecting method ofthe back most tooth based on the attitude of the brush.

FIG. 8 is a diagram illustrating another example of the detecting methodof the back most tooth based on the attitude of the brush.

FIG. 9 is a diagram illustrating an example of the detecting method ofthe back most tooth based on the trajectory of movement of the brush.

FIG. 10 is a diagram illustrating an example of the correcting processof brushing sites.

FIG. 11 is a diagram for describing the brush angle.

FIG. 12 is a diagram illustrating an example of outputting evaluationresults of the brushing.

FIG. 13 is a diagram illustrating a variation of a configuration of theelectric toothbrush device.

FIG. 14 is a schematic of a brushing support system according to anembodiment.

FIG. 15 is a schematic of an acceleration sensor and peripheral circuitaccording to an embodiment.

FIG. 16 is a flow chart for describing the brushing site estimationprocess according to an embodiment.

DETAILED DESCRIPTION

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention orinventions. The description of illustrative embodiments is intended tobe read in connection with the accompanying drawings, which are to beconsidered part of the entire written description. In the description ofthe exemplary embodiments disclosed herein, any reference to directionor orientation is merely intended for convenience of description and isnot intended in any way to limit the scope of the present inventions.The discussion herein describes and illustrates some possiblenon-limiting combinations of features that may exist alone or in othercombinations of features. Furthermore, as used herein, the term “or” isto be interpreted as a logical operator that results in true wheneverone or more of its operands are true.

Features of the present inventions may be implemented in software,hardware, firmware, or combinations thereof. The computer programsdescribed herein are not limited to any particular embodiment, and maybe implemented in an operating system, application program, foregroundor background processes, driver, or any combination thereof. Thecomputer programs may be executed on a single computer or serverprocessor or multiple computer or server processors.

Processors described herein may be any central processing unit (CPU),microprocessor, micro-controller, computational, or programmable deviceor circuit configured for executing computer program instructions (e.g.,code). Various processors may be embodied in computer and/or serverhardware of any suitable type (e.g., desktop, laptop, notebook, tablets,cellular phones, etc.) and may include all the usual ancillarycomponents necessary to form a functional data processing deviceincluding without limitation a bus, software and data storage such asvolatile and non-volatile memory, input/output devices, graphical userinterfaces (GUIs), removable data storage, and wired and/or wirelesscommunication interface devices including Wi-Fi, Bluetooth, LAN, etc.

Computer-executable instructions or programs (e.g., software or code)and data described herein may be programmed into and tangibly embodiedin a non-transitory computer-readable medium that is accessible to andretrievable by a respective processor as described herein whichconfigures and directs the processor to perform the desired functionsand processes by executing the instructions encoded in the medium. Adevice embodying a programmable processor configured to suchnon-transitory computer-executable instructions or programs may bereferred to as a “programmable device”, or “device”, and multipleprogrammable devices in mutual communication may be referred to as a“programmable system.” It should be noted that non-transitory“computer-readable medium” as described herein may include, withoutlimitation, any suitable volatile or non-volatile memory includingrandom access memory (RAM) and various types thereof, read-only memory(ROM) and various types thereof, USB flash memory, and magnetic oroptical data storage devices (e.g., internal/external hard disks, floppydiscs, magnetic tape CD-ROM, DVD-ROM, optical disk, ZIP™ drive, Blu-raydisk, and others), which may be written to and/or read by a processoroperably connected to the medium.

In certain embodiments, the present inventions may be embodied in theform of computer-implemented processes and apparatuses such asprocessor-based data processing and communication systems or computersystems for practicing those processes. The present inventions may alsobe embodied in the form of software or computer program code embodied ina non-transitory computer-readable storage medium, which when loadedinto and executed by the data processing and communications systems orcomputer systems, the computer program code segments configure theprocessor to create specific logic circuits configured for implementingthe processes.

The disclosure is divided into two sections. Section I discusses a firstelectric toothbrush and method for estimating a brushing site. SectionII discusses a second electric toothbrush and method for estimating abrushing site. To the extent a term, reference number, or symbol is useddifferently in different sections, context should be taken from therelevant section and not the other section.

Section I

FIG. 1 illustrates an example configuration of an electric toothbrushfor describing an embodiment, FIG. 2 illustrates an external appearanceof the electric toothbrush device of FIG. 1, and FIG. 3 illustrates aninternal configuration of the electric toothbrush of FIG. 1.

The exemplified electric toothbrush device illustrated in FIG. 1 andFIG. 2 includes a main body 2 that has a brush 5 that oscillates by thedrive of a built in motor 10, wherein the motor 10 that is the drivesource is placed in the main body 2, a charger 100 for charging the mainbody 2, and a display unit 110 for outputting the brushing result.

In this embodiment, the main body 2 is roughly a cylindrical shape, andalso serves as a handle part for the user to grip by hand when brushingthe teeth. In the main body 2, a switch S is provided for carrying outswitching of power on/off. Furthermore, a motor 10 that is the drivesource, a drive circuit 12, a rechargeable battery 13 that is the powersource, and a coil 14 for recharging is provided in the interior of themain body 2. When charging the rechargeable battery 13, by simplyplacing the main body 2 on the charger 100, it is possible to chargewithout contacting by electromagnetic induction. The drive circuit 12has a central processing unit (CPU) 120 of executing variouscalculations and control, a memory 121 for storing programs and varioussetting values, a timer 122, a data transmission module 123 and thelike. The data transmission module 123 carries out wirelesscommunication with the data receiving module 112 of the display unit110. The display unit 110 includes a display 111 for outputting datasuch as the brushing results received by the data receiving module 112.

Furthermore, in the interior of the main body, for example, anacceleration sensor 15 of multiple axes (here, the three axes x, y, z),an angular velocity sensor 16 of multiple axes (here, the three axes x,y, z) and geomagnetic sensor 17 of multiple axes (here, the three axesx, y, z), are provided for sensing the trajectory of movement and thethree-dimensional attitude of the brush 5.

The acceleration sensor 15 is disposed so that the x-axis is parallelwith respect to the brush surface, the y-axis coincides with thelongitudinal direction of the main body 2, and the z-axis isperpendicular to the brush surface. In other words, when the main bodyis placed in the charger 100, the gravitational acceleration vector isparallel to the y-axis; when the brush surface is facing upwards, thegravitational acceleration vector is parallel to the z-axis; and whenthe brush surface is facing to the back, the gravitational accelerationvector is parallel to the x-axis. The output of each axis of theacceleration sensor 15 is input to the CPU 120, and employed fordetecting the trajectory of movement and the attitude of the brush 5. Apiezoresistive type, a capacitance type, or a MEMS sensor of a thermalsensing type is preferably employed as the acceleration sensor 15. Sincethe MEMS sensor is very small, it can easily be incorporated into theinterior of the body 2. However, the format of the acceleration sensor15 is not limited to this, but a sensor such as an electrodynamic type,strain gauge type, or piezoelectric may be employed.

The angular velocity sensor 16 is disposed so that it can detect theangular velocity around the x-axis, the angular velocity around they-axis, and the angular velocity around the z-axis. The output of eachaxis out the angular velocity sensor 16 in input to the CPU 120, andemployed for detecting the trajectory of movement and the attitude ofthe brush 5. Any type of sensor such as an oscillation type, opticaltype, and mechanical type may be used as the angular velocity sensor 16,but a MEMS sensor can appropriately be used since it is small and caneasily be incorporated in main body 2.

The geomagnetic sensor 17 is disposed so that it can detect geomagnetismin the x-axis direction, the y-axis direction, and the z-axis direction.The output of each axis of the geomagnetic sensor 17 is input to the CPU120, and employed for detecting the trajectory of movement and theattitude of the brush 5. A MEMS sensor such as a MR (Magneto-resistive)element type, MO (Magneto-Impedance) element type, and a hole elementtype is preferably employed as the geomagnetic sensor 17. The sensorsdiscussed above can be used to detect a trajectory or attitude.Accordingly, these sensors (together or alone, depending on theembodiment) may be referred to as a “trajectory detecting module” and/oran “attitude detecting module.” In other embodiments, other devices canbe used to detect trajectory or attitude.

Furthermore, a load sensor 18 for sensing the brush pressure (loadacting on the brush) is included in the interior of the main body 2.Although any type such as a strain gauge, a load cell, or a pressuresensor can be used, a MEMS sensor can be appropriately used as the loadsensor 18 since it is small and can be easily incorporated in the mainbody 2.

The brush 5 includes a stem part 20 fixed to the main body 2 side, and abrush component 21 mounted on the stem part 20. Brush bristles 210 areattached to the top portion of the brush component 21. Since the brushcomponent 21 has consumable parts, it is configured to be freelydetachable with respect to the stem part 20 so that it can be replacedwith a new one.

In this embodiment, the stem part 20 is made from a resin material, andattached to the main body 2 via an elastic member 202 made from anelastomer. The stem part 20 is a cylindrical member in which the tip(tip end of the brush side) is closed, and has a bearing 203 in the tipend of the interior of the tube. The tip of the eccentric shaft 30connected to the rotary shaft 11 of the motor 10 is inserted into thebearing 203 of the stem part 20. The eccentric shaft 30 has a weight 300near the bearing 203, and the center of gravity of the eccentric shaft20 is shifted from the center of rotation. Note that a minute clearanceis provided between the tip of the eccentric shaft 30 and the bearing203.

In this embodiment, the CPU 120 is provided in the motor 10, and rotatesthe rotary shaft 11 of the motor 10. Although the eccentric shaft 13also rotates along the rotation of the rotary shaft 11, the eccentricshaft 30 carries out the movement such as turning about the axis ofrotation since the center of gravity is shifted. Thus, the tip of theeccentric shaft 30 repeatedly collides against the inner wall of thebearing 203, and the stem part 20 and the brush component 21 mountedthereon oscillates (moves) at high speed. That is, the motor 10 plays arole of the drive module for oscillating (moving) the brush 5 and theeccentric shaft 30 plays a role of a movement transmission mechanism(movement conversion mechanism) for converting the output (rotation) ofthe motor 10 to oscillation of the brush 5.

The user can carry out brushing by applying the hand of the main body 2,that is, the brush bristles 210 for oscillating at high speed, to theteeth. Note that, the CPU 210 monitors the continuous operation time byusing the timer 122, and automatically stops the oscillation of thebrush 5 after a predetermined amount of time (for example, 2 minutes)has elapsed.

The way food residue and plaque are attached is different at each site,therefore the effective brushing operation is different at each site.Thus, it is preferable to carry out an evaluation at each site ofwhether or not appropriate brushing is being carried out. Therefore, theelectric toothbrush device 1 performs a brushing evaluation of each siteby estimating the brushing site based on the trajectory of movement andthe attitude of the brush 5, by using an acceleration sensor 15, angularvelocity sensor 16, and a geomagnetic sensor 17. Various evaluationitems are considered, but here an evaluation of three items, thebrushing time, brush angle, and brush pressure, is carried out.

As illustrated in FIG. 4, the upper and lower teeth surfaces are dividedinto 16 sections of a “maxillary front buccal surface”, “maxillary frontlingual surface”, “maxillary left buccal surface”, “maxillary leftlingual surface”, “maxillary left occlusal surface”, “maxillary rightbuccal surface”, “maxillary right lingual surface”, “maxillary rightocclusal surface”, “mandibular front buccal surface”, “mandibular frontlingual surface”, “mandibular left buccal surface”, “mandibular leftlingual surface”, “mandibular left occlusal surface”, “mandibular rightbuccal surface”, “mandibular right lingual surface”, and a “mandibularocclusal surface”. However, division of the teeth surface is not limitedto this, and may be divided into a rougher division or a finer division.

The flow of the brushing evaluation will be described specifically withreference to FIG. 5. Note that, the process described hereafter is aprocess performed according to the program stored in the memory 121 ofthe CPU 120, unless otherwise stated.

When the power supply of the main body is ON, the CPU 120 detects thetrajectory of movement and the attitude of the brush 5 based on theoutput of the acceleration sensor 15, the angular velocity sensor 16,and the geomagnetic sensor 17 (Step S10). Then, the CPU 120 estimatesthe brushing site by using the trajectory detected by at least step S10(Step S20). Then, the CPU 120 carries out detection of the back mosttooth when the brushing site estimated by step S20 is the back side siteof the teeth rows end (Step S30). Then, the CPU 120 corrects thebrushing site of each position in the trajectory of movement of thebrush 5 based on the position of the back most tooth detected by stepS30 (Step S40). Then, the CPU 120 carries out estimation of the brushangle and sensing of the brush pressure (Step S50). The information ofthe brushing site, the brush angle and the brush pressure is recorded inthe memory 121 associated with a position in the trajectory of the brush5.

The process of steps S10 to S50 are repeatedly performed, when the powersupply is turned OFF or the continuous operation time reaches apredetermined time (for example 2 minutes), the brushing results at eachsite are evaluated based on brushing information (brushing site, brushangle, brush pressure) recorded in the memory 121, and outputs theevaluation results to the display unit 110 (Step S60).

Hereinafter, the process of step S10 to S60 will be described in detail.

The CPU 120 acquires outputs Ax, Ay and Az of the x-axis, y-axis andz-axis respectively, from the acceleration sensor 15; acquires outputsBx, By and Bz of the x-axis, y-axis and z-axis respectively, from theangular velocity sensor 16; and acquires outputs Cx, Cy and Cz of thex-axis, y-axis and z-axis respectively, from the geomagnetic sensor 17.Ax displays the acceleration component of the x-axis direction, Aydisplays the acceleration component of the y-axis direction, and Azdisplays the acceleration component of the z-axis direction. Bx displaysthe angular velocity component about the x-axis, By displays the angularvelocity component about the y-axis, Bz displays the angular velocitycomponent about the z-axis. Cx displays the magnetic component of thex-axis direction, Cy displays the magnetic component of the y-axisdirection, Cz displays the magnetic component of the z-axis direction.

When the size of the resultant vector A (Ax, Ay, Az) is smaller than apredetermined threshold value equivalent to the gravitationalacceleration, the CPU 120 determines that the main body 2 is stationary,and the output Ax, Ay and Az of the acceleration sensor 15 is made to bethe attitude vector D (Dx, Dy, Dz) for displaying a three dimensionalattitude of the brush.

When the size of the resultant vector A (Ax, Ay, Az) is greater than thethreshold value, the CPU 120 determines that the main body 120 ismoving. The angular variation amount of the main body 2 is obtainedabout each axis of the x-axis, y-axis and z-axis from when the main body2 was most recently determined to be stationary. Based on the outputsBx, By and Bz of the angular velocity sensor, rotated at the angularvariation amount for obtaining a resultant vector A (Ax, Ay, Az) of whenthe main body 2 was most recently determined to be stationary, theattitude vector D (Dx, Dy Dz) is obtained.

The attitude vector D (Dx, Dy, Dz) obtained as above, corresponds to thegravitational acceleration. Note that the angular velocity sensor 16generally results in drift, and after the error in calculation of theangular velocity amount is accumulated, the CPU 120 carries out a zerocalibration of the angular velocity sensor 16 from time to time by usingoutput of the acceleration sensor 15 and the geomagnetic sensor 17.

Furthermore, the CPU 120 obtains the variation amount of each axisdirection of the x-axis, y-axis and z-axis, based on the accelerationcomponent obtained by removing the gravitational component from theoutput Ax, Ay and Az of the acceleration sensor 15. The gravitationalacceleration included in the outputs Ax, Ay and Az can use the attitudevector D (Dx, Dy, Dz). Also, the CPU 120 obtains the trajectory of themovement of the brush 5 by taking into consideration the position of thebrush 5 in the main body 2 that is determined from the three dimensionalattitude of the brush 5.

The CPU 120 estimates the brushing site at each position on thetrajectory of movement of the brush 5 by carrying out matching of thetrajectory of movement of the brush 5 and the teeth row surface. (Inthis regard, the CPU 120 is sometimes referred to as a “site estimatingmodule,” though other processors can be used to estimate a site.)Although the estimation accuracy of the brushing sites increases as thetrajectory is accumulated, if the starting site of brushing is reportedto the user, it is possible to accurately carry out estimation of thebrushing site from a relatively early stage.

Note that, by taking this into consideration together with the attitudeof the brush 5, it is possible to estimate the brushing site with ahigher accuracy. For example, it is possible to determine whether it isthe maxillary or the mandibular based on the z-axis direction componentDz of the attitude vector D. As illustrated in FIG. 6, it is noted thatwhen brushing the maxillary teeth, the brushing surface facesconsiderably upwards, and when brushing the mandibular teeth, the brushsurface faces considerably downwards, and it is possible to detect thatwhen Dz>0 it is the maxillary, and when Dz≤0 it is the mandibular.

When the estimated brushing site is the back side site of the teeth rowends, that is, the “maxillary left buccal surface”, “maxillary leftlingual surface”, “maxillary left occlusal surface”, “maxillary rightbuccal surface”, “maxillary right lingual surface”, “maxillary rightocclusal surface”, “mandibular left buccal surface”, “mandibular leftlingual surface”, “mandibular left occlusal surface”, “mandibular rightbuccal surface”, “mandibular right lingual surface”, and a “mandibularocclusal surface”, the CPU 120 carries out detection of the back mosttooth. (In this regard, the CPU 120 is sometimes referred to as a “backmost tooth detecting module,” though other processors can be used indetecting a back most tooth.)

FIG. 7 illustrates and example of a detection method of the back mosttooth when the estimated brushing site is the “mandibular left buccalsurface” and the “mandibular left lingual surface”, and FIG. 8illustrates and example of a detection method of the back most toothwhen the estimated brushing site is the “mandibular left occlusalsurface”.

When brushing the side surface S0 of the maxillary left back most tooth,typically, the brush 5 reaches the side surface S0 of the back mosttooth by moving to the back side along the mandibular left teeth rowends.

When the brush 5 is moved along the “mandibular left buccal surface” forexample, the brush 5 rapidly rotates about the x-axis in a processleading to the side surface S0 from the buccal surface S1 of the backmost tooth, as illustrated in FIG. 7. There, when the estimated brushingsite is the “mandibular left buccal surface”, and when the variationamount θa of the attitude about the x-axis of the brush 5 is greaterthan a predetermined threshold value on the basis of the attitude of thebrush 5 along the teeth row ends of the “mandibular left buccalsurface”, it is possible to detect the back most tooth. The attitude ofthe brush 5 along the teeth row surface of the mandibular left buccalsurface that serves as a reference, for example, can be an average ofthe attitude of the brush 5 at each position estimated as the“mandibular left buccal surface” in the trajectory of the brush 5.

When the brush 5 moves along the “mandibular left lingual surface”, thebrush 5 rapidly rotates about the x-axis in a process leading to theside surface S0 from the back most tooth lingual surface S2. There, whenthe estimated brushing site is the “mandibular left lingual surface”,and when the variation amount θb of the attitude about the x-axis of thebrush 5 is greater than a predetermined threshold value on the basis ofthe attitude of the brush 5 along the teeth row ends of the “mandibularleft lingual surface” and on the basis of the attitude of the brush 5,it is possible to detect the back most tooth.

Furthermore, when the brush 5 moves along the “mandibular left occlusalsurface”, the brush 5 rapidly rotates about the x-axis in a processleading to the side surface S0 from the back most tooth occlusal surfaceS3, as illustrated in FIG. 8. There, when the estimated brushing site isthe “mandibular left occlusal surface”, and when the variation amount θcof the attitude about the x-axis of the brush 5 is greater than apredetermined threshold value on the basis of the attitude of the brush5 along the teeth row ends of the “mandibular left occlusal surface”, itis possible to detect the back most tooth.

When the estimate brushing site is the “mandibular right buccalsurface”, “mandibular right lingual surface”, “maxillary left buccalsurface”, “maxillary left lingual surface”, “maxillary right buccalsurface”, and the “maxillary right lingual surface”, in the same manneras the detection method in FIG. 7, and furthermore, when the brushingsite is the “mandibular right occlusal surface”, “maxillary leftocclusal surface”, and the “maxillary right occlusal surface”, in thesame manner as the detection method illustrated in FIG. 8, it ispossible to detect the back most tooth based on the variation ofattitude of the brush 5.

The detection of the back most tooth above focuses on the threedimensional attitude of a specific brush 5 in brushing of the back mosttooth, but the detection method of the back most tooth illustrated inFIG. 9 focuses on the movement of a specific brush 5 in brushing of theback most tooth.

Normally, it is difficult to move the brush 5 to the back most toothalong the teeth row ends due to interference of biological tissue in themouth. Furthermore, after the brush 5 reaches the back most tooth bymoving to the teeth side along the teeth row ends, the brush 5 is movedagain to the front side. There, as illustrated in FIG. 9, in thetrajectory portion of the back side portion of the teeth row ends ofamong the trajectory of movements of the brush 5, and of among a returnpoint RP1, RP2, and RP3 of movement of the brush 5, it is possible todetect the return point RP3 of the movement of the brush 5 in the backmost tooth as the back most tooth. Note that, the trajectory portion ofthe “mandibular left buccal surface” in FIG. 9 is illustrated, but evenfor trajectory portions of another back side portion, a returning pointof the movement of the brush 5 in the same back most tooth can bedetected as the back most tooth.

The CPU 120 is configured so as to detect the back row teeth byindependently carrying out detection of the back most tooth based onvariation of the attitude of the brush 5 above, detection of the backmost tooth based on the trajectory of the brush 5 respectively, andpreferably is configured so as to detect the back most tooth based onvariation of the attitude of the brush 5 at the returning point of theback most side of movement of the brush 5. Thus, it is possible tofurther increases the detection accuracy of the back most tooth.

FIG. 10 illustrates an example of a correction process of the brushingsites at each position on the trajectory of movement of the brush 5.

For each position P1 to P11 on the trajectory of movement of the brush5, the brushing sites of brush position P1 to P4 is estimated as the“mandibular right buccal surface”, the brushing sites P5 to P7 areestimated as the “mandibular front buccal surface”, and the brushingsites P8 to P11 are estimated as the “mandibular left buccal surface”.Also, for position P12 of the brush 5 detected by the following stepS10, the brushing site is estimated as the “mandibular left buccalsurface, and the back most tooth is detected in the position P12.

The CPU 120 updates the position of the mandibular left back most toothto position P12 in the trajectory of movement of the brush 5 when theback most tooth are detected by position P12. Also, the CPU 120 correctsthe brushing site of each position P1 to P11 estimated by the matchingof the teeth row ends and the trajectory of movement of the brush 5,based on the position of the updated back most tooth. In the exampleillustrated, due to the correction, P1 to P3 are corrected to the“mandibular right buccal surface”, P4 to P8 are corrected to the“mandibular front buccal surface”, and P9 to P11 are corrected to the“mandibular left buccal surface”.

Thus, when the back most tooth is detected, the position of the backmost tooth in the trajectory of movement of the brush 5 accumulated tothat point, can further increase the estimation accuracy of the brushingsite by matching of the teeth row ends and the following trajectory, dueto correcting the brushing site at each position in the trajectory basedon the position of the updated back most tooth.

The CPU 120 estimates the brush angle based on the attitude of the brush5 detected by step S10. The brush angle is the angle per brush againstthe tooth axis (axis along the head and root of the tooth). The upperpart of FIG. 11 illustrates a state in which the brush angle=15 degrees,the middle part illustrates a state in which the brush angle=45 degrees,and the lower part illustrates a state in which the brush angle=90degrees. When effectively scraping out food residue and plaque frombetween the teeth and the periodontal pockets, the bristles of the brushmay move the brush so as to enter between the teeth and the periodontalpockets. Therefore, a brush angle in the range of 35 degrees to 55degrees is preferred.

The brush angle, for example, can be estimated from the z-axis directioncomponent Dz of the attitude vector D; when the brush angle is about 90degrees Dz will be about 0, and as the brush angle decreases theabsolute value of Dz increases, which is because the value of Dz changessignificantly corresponding to the brush angle. The brush angle may becalculated in a continuous quantity, or it may be a rough estimate suchas “less than 35 degrees”, “35 to 55 degrees”, and “55 degrees orabove”.

Furthermore, the CPU 120 calculates the brush pressure based on theoutput of the load sensor 18. When the brush pressure is too mall theplaque removal power decreases, and conversely, when it is too largethere is a possibility of problems such as a decrease in the brush lifeand an increased burden on the gums occurring. Since the brush pressureof an electric toothbrush may be less than a normal toothbrush, mostpeople who started using an electric toothbrush said there was atendency of excessive brush pressure. The optimum value of brushpressure is about 100 g.

The CPU 120 evaluates the brushing results of each site based on thebrushing information (brushing site, brush angle, brush pressure) ofeach position in the trajectory of movement of the brush 5 recorded inthe memory 121, and outputs the evaluation results to the display unit110 (Display 111). Here, an evaluation of the brushing time, brushangle, and brush pressure are carried out.

The brushing time of every site is counted by counting up every site ofthe brushing sites of each position in the trajectory of the brush 5.For example, if the process of step S10 to S50 is performed once for 0.1seconds, each time the brushing site is counted up, the brushing time ofthe site is counted up by +0.1 seconds.

The brush angle of every site is aggregated at every site of the brushangle of each position based on the brushing site of each position inthe trajectory of movement of the brush 5, and for example, iscalculated as the average value. Likewise, the brush pressure of everysite is aggregated at every site of the brush angle of each positionbased on the brushing site of each position in the trajectory ofmovement of the brush 5, and for example, is calculated as the averagevalue.

The evaluation of the brushing time, brush angle, and brush pressure ofevery site is not particularly limited. The brushing time can beevaluated in three stages for example, 7 seconds is “insufficient”, 7seconds to 15 seconds is “good”, and greater than 15 seconds is“excessive”. Furthermore, the brush angle can be evaluated in threestages for example, “less than 35 degrees” is “insufficient”, “35degrees to 55 degrees” is “good”, and “55 degrees or above” is“excessive”. Furthermore, the brush pressure can be evaluated in threestages for example, less than 80 g is “insufficient”, 80 g to 150 g is“good”, and greater than 150 g is “excessive”. These evaluation resultsare transmitted to the display unit 110.

The output of the evaluation results in the display unit 110 are notparticularly limited. For example, as illustrated in FIG. 12, the upperand lower teeth are displayed, and each site can be displayed by a color(“insufficient” is white, “good” is yellow, “excessive” is red, and thelike) corresponding to the evaluation results of each site by seeing adisplay as such, the user can intuitively understand when the brushingof some site in a tooth row is insufficient or excessive.

Also, since the position of the back most tooth in the trajectory ofmovement of the brush 5 is detected, it is possible to evaluate theresults of the brushing of the back most tooth as a detailed site ofamong the back side portion of the teeth row ends. The CPU 120 carriesout an evaluation of whether or not the back most tooth was brushedbased on the presence or absence of the detection of the back mosttooth, and furthermore, an evaluation of the brushing time, brush angle,and brush pressure of the back most tooth based on the brush positionthat detected the back most tooth and the brushing information near thatposition. The back most tooth in which there is a tendency to leaveun-brushed is detected, and by presenting the evaluation resultsregarding the brushing of the back most tooth to the user, it ispossible to promote health of the teeth.

As described above, according to the electric toothbrush device 1, sinceit is possible to detect the back most tooth with an acceleration sensor15 and the like for detecting the trajectory of movement and theattitude of the brush 5, the configuration of the electric toothbrush 1can be made to be simple. Also, when the back most tooth is detected,the position of the back most tooth in the trajectory of movement of thebrush 5 accumulated to that point are updated, and it is possible toaccurately estimate the brushing site since the brushing site at eachposition in the trajectory is correct based on the position of theupdated back most tooth.

FIG. 13 illustrates a configuration of a variation of the electrictoothbrush 1.

The example illustrated in FIG. 13 provides a camera 19 in the end ofthe y-axis direction of the brush 5. Any camera that can acquire imageinformation in the mouth, such as a visible light camera or an infraredcamera, can be employed as the camera 19. The infrared camera monitorsthe emitted heat (also referred to as thermography). Since the mouth canbe dark while brushing, an infrared camera is more preferable than avisible light camera. Since the contour of the uvula may be understoodas described below, the resolution of the camera may be not very high.

The CPU 120 acquires an image from the camera 19 in addition to theoutput of the acceleration sensor 15, angular velocity sensor 16, andgeomagnetic sensor 17 in step S10 (FIG. 5), the uvula can be detectedfrom the image. The detection of the uvula is possible using awell-known image analysis technique. For example, contour detection ofthe uvula by edge extraction or Hough transform, or detection of theuvula by pattern matching and the like is considered.

When the brush 5 is on the lingual side, there is a high probabilitythat the uvula will appear in order for the end of the brush 5 to facetowards the throat. On the other hand, when the brush 5 on the buccalside, the uvula does not appear in the image. Therefore, CPU 120determines it to be “lingual” when the uvula is not detected, and as“buccal” when the uvula is detected.

Note that, although the uvula is the detected object, the attitude andposition of the brush may be determined by recognizing other sites inthe mouth (for example, tongue, throat, teeth, gums and the like). Forexample, if the tongue and throat appear in the image, it can bedetermined that the brush is in the lingual side.

Thus, in addition to the trajectory of movement of the brush 5 detectedbased on the output of the acceleration sensor 15, angular velocitysensor 16, and geomagnetic sensor 17, by complementarily using the imageof the camera 19 in estimation of the brushing site, it is possible tofurther increase the estimation accuracy of the brushing site.

Note that, a light sensor provided in the brush portion is preferable toa camera. Since light is detected in the lingual side whereas the buccalside is completely dark, it is possible to determine both by analyzingthe output of the light sensor.

The embodiments described herein are in all respects examples and are inno way considered to be limited thereto. The scope of the presentinvention is indicated by the scope of the patent claims and is intendedto include all alternatives within equivalent meaning and scope to thepatent claims.

As described above, the following matters are disclosed in the presentspecification. The disclosed electric toothbrush includes: a trajectorydetecting module for detecting the trajectory of movement of a brush; anattitude detecting module for detecting the attitude of the brush; asite estimating module for estimating the brushing site at each positionin the trajectory, using a trajectory detected by at least thetrajectory detecting module; and a back most tooth detecting module fordetecting the back most tooth based on change of attitude detected bythe attitude detecting module, wherein the site estimating moduleupdates the position of the back most tooth in the trajectory detectedby the trajectory detecting module, when the back most tooth is detectedby the back most tooth detecting module, and corrects the brushing sitesat each position on the trajectory based on the position of the updatedback most tooth.

Furthermore, in the disclosed electric toothbrush device, the back mosttooth detecting module, in reference to the attitude of the brush alongthe teeth row surface of the back side site, detects the back most toothbased on a difference between the reference of attitude detected by theattitude detecting module.

Furthermore, in the disclosed electric toothbrush device, the back mosttooth detecting module detects the returning point at the back most sideof movement of the brush as the back most tooth, in the trajectoryportion in which the brushing site estimated by the site estimationmodule of among the trajectory detected by the trajectory detectingmodule is the back side site of the teeth row end.

Furthermore, in the disclosed electric toothbrush device, the siteestimation module further uses an attitude detected by the attitudedetecting module, and estimates the brushing site at each site on thetrajectory detected by the trajectory detecting module.

Furthermore, the disclosed electric toothbrush device further comprisesan evaluation output module for evaluating and outputting brushingresults of every site.

Section II

A brushing site can be estimated based on the detection signal of anacceleration sensor, but the accuracy of such a method can beinsufficient. For example, when a user moves his face and the electrictoothbrush together in the state of inserting a brush unit into hismouth, although the tooth that the brush unit is contacting does notchange, a change occurs in the detection signal of the accelerationsensor. Because of this, there is a possibility that the brushing sitecan be estimated falsely.

Furthermore, when the user moves only his face in the state of insertingthe brush unit into his mouth, although a change does not occur in thedetection signal of the acceleration sensor, the tooth that the brushunit is contacting changes. Because of this, there is a possibility thatthe brushing site can be estimated falsely. Accordingly, there is needto address such issues to provide improved brushing site estimationaccuracy.

The electric toothbrush of the present invention is provided with adriving module that oscillates the brush unit, an acceleration sensor, afirst signal achieved from a frequency of a first threshold or more fromthe output signal of the acceleration sensor, a signal extraction modulethat extracts a second signal achieved from a frequency of a secondthreshold or less, a brushing site estimation module by the brush unitbased on the output signal of the acceleration sensor, and a correctionmodule that corrects the brushing site estimated by the brushing siteestimation module based on the amplitude of the first signal and theamplitude of the second signal.

The brushing site estimation method of the present invention is abrushing site estimation method by the electric toothbrush having thedriving module that oscillates the brush unit and the accelerationsensor and is provided with a signal extraction step that extracts thefirst signal achieved from the frequency of the first threshold or moreand the second signal achieved from the frequency of the secondthreshold or less, a brushing site estimation step that estimates thebrushing site by the brush unit based on the output signals of theacceleration sensor, and a correction step that corrects the brushingsite estimated by the brushing site estimation step.

FIG. 14 is a diagram illustrating the schematic structure of thebrushing support system for describing an embodiment of the presentinvention. This system is provided with an electric toothbrush 31, acharging unit 3100, and a display unit 3110.

The electric toothbrush 31 is provided with a main body 32 having amotor 311 built in as a driving module that oscillates a brush unit 33,and the brush unit 33 that oscillates by the driving of the motor 311.

The main body mainly exhibits a cylindrical shape and also has a handleportion for the user to grasp with their hand when brushing teeth. Thebrush unit 3 has a brush portion arranged by a plurality of brush groupsbundling several hairs, and has a detachable structure to a main body32.

A switch 312 for performing a power on/power off is provided on the mainbody 32 of the electric toothbrush 31.

The motor 311 (for example, a direct current motor), a charging battery313 that is the power source for supplying electricity to each portion,a CPU (Central Processing Unit) 314, and the like are provided on theinner portion of the main body 32 of the electric toothbrush 31.

The CPU 314 carries out each type of calculation and control. A memory315, a data sending module 316, a display module 317, and the like areconnected to the CPU 314. The memory 315 houses a program, each type ofset value, and the like. The data sending module 316 performs wirelesscommunication between a data receiving module 3111 of the display unit3110. The display unit 317 displays the brushing effect and the like.

A voltage monitor 318 for detecting the output voltage (the remainingbattery) of the charging battery 313, an acceleration sensor 319 forsensing the attitude of the electric toothbrush 31, and a filter module320 that filter processes the output signal of the acceleration sensor319 are further provided on the inner portion of the main body 32 of theelectric toothbrush 31.

For example, a multi-axis (here the 3 axes of x, y, and z) accelerationsensor is used in the acceleration sensor 319. The output of each axesof the acceleration sensor 319 is input into the CPU 314 and is used todetect the 3 dimensional attitude of the brush unit 33.

A piezoresistive type, a capacitance type, or a micro electro mechanicalsystems (MEMS) heat sensing type can be preferably used for theacceleration sensor 319. Building the MEMS sensor on the inner portionof the main body 32 is simple since is extremely small-sized. However,the form of the acceleration sensor 319 is not limited to this and asensor of an electrodynamic formula, a strain gage formula, a voltageformula, and the like may also be used.

Furthermore, while not specifically shown, it is good to provide acorrective circuit to correct the balance of the sensitivity of thesensor of each axis, the sensitivity of the temperature characteristics,the temperature drift, and the like. Furthermore, a band pass filter(low pass filter) for removing a dynamic acceleration component andnoise may be provided. Furthermore, noise may be reduced by smoothingthe output waveform of the acceleration sensor.

The system of the present embodiment mounts the main body 32 and isprovided with the charging unit 3100 for charging the electrictoothbrush 31 and the display unit 3110 for outputting the brushingeffect. When charging the charging battery 313, it is possible to chargeby non-contact electromagnetic induction just by mounting the main body32 on the charging unit 3100.

The display unit 3110 is provided with a data receiving module 3111 thatperforms wireless communication with the data sending module 316provided on the inside of the main body 32 of the electric toothbrush31, and a display 3112 for outputting the data of the brushing resultand the like received from the receiving module 3111.

FIG. 15 is a diagram schematically illustrating the acceleration sensor319 and a peripheral circuit thereof according to one embodiment. Asillustrated in FIG. 15, the filter module 320 is connected to theacceleration sensor 319. The CPU 314 is connected to the filter module320. Furthermore, the acceleration sensor 319 is connected directly tothe CPU 314.

The filter module 320 receives the output signal from the accelerationsensor 319 and has a Band Pass Filter (BPF) 3201 that passes throughonly the signal of the specified frequency zone a High Pass Filter (HPF)3202 connected in parallel to the BPF 3201, and a low pass filter (LPF)3203.

The HPF 3202 passes through only a first 3202P signal of a frequency ofa specified cut off frequency (for example, several hundred to severalthousand Hz) or more that is a first threshold out of an input signalfrom the BPF 3201, and outputs to a processor 3141. The first thresholdis the first signal 3202P output from the HPF 3202 being set to a largevalue to an extent reflecting a moveable component of the electrictoothbrush 31 occurring by the brush unit 3 being oscillated at highspeed by the motor 311.

The LPF 3203 passes through only a second 3203P signal of a frequency ofa specified cut off frequency (for example, several Hz) or less that isa second threshold out of an input signal from the BPF 3201, and outputsto a processor 3142. The second threshold is the second signal 3203Poutput from the LPF 3203 being set to a small value to an extentreflecting when the electric toothbrush 31 moves much more slowly thanthe oscillation of the brush unit 33 and a moveable component.

The HPF 3202 and the LPF 3203 function as a signal extraction modulethat extract the first signal 3202P and the second signal 3203P from theoutput signal of the acceleration sensor 319. The first signal 3202P isa high frequency signal to the second signal 3203P. In other embodiment,the signal extraction module can be any device for obtaining the firstand second signals from the output of the acceleration sensor.

The CPU 314 is provided with the processor 3141, the processor 3142, abrushing site estimation module 3143, and a correction module 3144. Eachof these modules is function block realized by carrying out the programthat the CPU 314 housed in the memory 315.

The processor 3141 seeks the amplitude of each waveform of thehigh-frequency first signal 3202P output from the HPF 3202 andcalculates the variation amount in the specified period on the soughtamplitude.

The processor 3142 seeks the amplitude of each waveform of the lowfrequency second signal 3203P output from the LPF 3203.

The brushing site estimation module 3143 can use the algorithm describedin Japanese Unexamined Patent Application Publication No. 2009-240760,or Japanese Unexamined Patent Application Publication No. 2011-156204,which are hereby incorporated by reference in their entireties. Thesealgorithms are based on the output signal from the acceleration sensor319 to estimate the site being contacted by the brush portion of thebrush unit (the brushing site).

The correction module 3144 corrects the brushing site estimated by thebrushing site estimation module 3143 based on the amplitude of the firstsignal 3202P sought by the processor 3141 and the amplitude of thesecond signal 3203P sought by the processor 3142.

FIG. 16 is a flow chart for describing the estimation process of thebrushing site in the electric toothbrush 31 according to an embodiment.When the switch 312 is operated and the power supply of the electrictoothbrush 31 is ON, the CPU 314 performs a process that formats eachportion, and the brushing site estimation module 3143 detects theattitude (slant) of the brush based on the output of the accelerationsensor 319 (step S31).

Next, the brushing site estimation module 3143 estimates the brushingsite based on the attitude detected by the step S31 (step S32).

Next, the correction module 3144 determines, based on the output signalof the processor 3141, whether or not the amplitude of the first signal3202P has changed, that is to say, whether or not the variation amountof the amplitude of the first signal 3202P is at the third threshold orabove (step S33).

During teeth brushing, the brush unit 33 will move along with the row ofteeth while contacting the row of teeth. In a state in which the brushportion of the brush unit 33 is contacting one tooth contained in therow of teeth, the amplitude of the first signal 3202P will change at apractically fixed value. That is to say, the variation amount ofamplitude of the first signal 3202P is small in a fixed time.

When the brush unit 33 moves along the row of teeth, the brush portionpasses through the interdental space. When the brush portion passesthrough the interdental space, the amplitude of the first signal 3202Pgets smaller in this time because time occurs where the brush unit isnot in contact with the tooth.

That is to say, from a state where the brush portion is in contact withan arbitrary tooth, when moving the brush portion from this tooth to aneighboring tooth, the amplitude of the first signal 3202P returns to afirst value after the amplitude changes to a second value smaller thanthe first value from the state of the first value. In this manner, thevariation amount of amplitude of the first signal 3202P gets larger in afixed time.

Therefore, it can be distinguished by the size of the variation amountof amplitude of the first signal 3202P whether the brush unit 33 isstill regarding the tooth or whether the brush unit 33 is movingregarding the tooth. Because of this distinguishing, the step S33processing is performed.

If the determination of the step S33 is YES, it can be determined thatthe brush unit 33 is moving with respect to the tooth, and if thedetermination of the step S33 is NO, it can be determined that the brushunit 33 is still with respect to the tooth.

When the determination of the step S33 is YES, the correction module3144 determines whether or not the amplitude of the second signal 3203Pis large, that is to say, whether or not the amplitude of the secondsignal 3203P exceeds a fourth threshold based on the output signal ofthe processor 3142 (step S34).

The pattern in which the brush unit 33 moves with respect to the toothhas a first pattern in which only the electric toothbrush moves in astate where the face is still and a second pattern in which the only theface moves in a state where the electric toothbrush 31 is still.

The amplitude of the second signal 3203P in the first pattern becomeslarger because the electric toothbrush is moving. On the other hand, theamplitude of the second signal 3203P in the second pattern becomes asufficiently smaller value than the first pattern (a value of the fourththreshold or less) because the electric toothbrush 31 is still.

Therefore, it can be distinguished whether it is the first pattern orthe second pattern by the determination in step S34.

When the determination of the step S34 is YES (the amplitude of thesecond signal 3203P exceeds the fourth threshold), the correction module3144 distinguishes that “the face is still and the brush portion ismoving” (step S35).

When it is distinguished that “the face is still and the brush portionis moving,” the reliability of the brushing site estimated based on theoutput signal of the acceleration sensor 319 is high. Because of this,the correction module 3144 makes the brushing site estimated by thebrushing site estimation module 3143 effective as it is after the stepS35 (step S36).

When the determination of the step S34 is NO (the amplitude of thesignal 3203P is the fourth threshold or less), the correction module3144 distinguishes that “the face is moving and the brush portion isstill” (step S37).

When it is distinguished that “the face is moving and the brush portionis still,” the reliability of the brushing portion estimated based onthe output signal of the acceleration sensor 319 gets low. Because ofthis, the correction module 3144 corrects (substitutes) the brushingsite estimated by the brushing site estimation module 3143 to the siteneighboring that site (a site estimated to not yet be brushed) after thestep S37 (step S38).

When the determination of step S33 is NO, the correction module 3144determines whether or not the amplitude of the second signal 3203P issmall, that is to say, whether or not the amplitude of the second signal3203P is the fourth threshold or less based on the output of theprocessor 3142 (step S39).

When the correction module 3144 determines that the amplitude of thesecond signal 3203P to be small (step S39: YES), it distinguishes that“the face is still and the brush portion is also still” (step S40). Inthis case, the reliability of the brushing site estimated based on theoutput of the acceleration sensor 319 is high. Because of this, thecorrection module 3144 makes the brushing site estimated by the brushingsite estimation module 3143 effective as it is (step S41).

When the correction module 3144 determines that the amplitude of thesecond signal 3203P is not small (step S39: NO), it distinguishes that“the face and the brush are moving integrally” (step S42). In this case,the reliability of the brushing site estimated based on the output ofthe acceleration sensor 319 is low. Because of this, the correctionmodule 3144 corrects (substitutes) the brushing site estimated by thebrushing site estimation module 3143 to the site estimated just before(step S43). That is to say, the correction module 3144 does not performa renewal of the brushing site, but performs a process maintaining thebrushing site estimated just before.

The CPU 314 is estimated as above, and outputs the corrected brushingsite to the display unit 3110 (the display 3112) via the data sendingmodule 316 (step S44).

As above, it is possible to improve the brushing site estimationaccuracy based on the amplitude of a high frequency component and theamplitude of a low frequency component output from the accelerationsensor 319 provided on the electric toothbrush 31. Therefore, it becomespossible to perform effective brushing support.

Each process performed by the CPU 314 in the present embodiment can alsobe presented as a program for carrying out on a computer. Furthermore,the process performed by the filter 320 can also be presented as aprogram for carrying out on a computer. This manner of program isrecorded to a non-temporary (non-transitory) recording medium as aprogram that can be read by the computer.

This manner of “recording medium that can be read by a computer” is, forexample, an optical medium such as a Compact Disc-ROM (CD-ROM), andincludes magnetic recording mediums such as a memory card. Furthermore,this manner of program can also be presented by download via a network.

It should be thought that all of the points of the embodiment shown thistime are examples and are not limited. The scope of the presentinvention is not the above description, but is illustrated in the scopeof claims, and all of the changes having meaning equal to the scope ofclaims and within the scope are implied to be included.

As described above, the below matters are shown in the presentspecification. The electric toothbrush shown is comprised of a drivingmodule that oscillates the brush unit, an acceleration sensor, a signalextraction module that extracts the first signal derived from thefrequency being at the first threshold or more and the second signalderived from the frequency being at the second threshold or below fromthe output signal of the acceleration sensor, a brushing site estimationmodule that estimates the brushing site by the brush unit based on theoutput signal of the acceleration sensor, and a correction module thatcorrects the brushing site estimated by the brushing site estimationmodule based on the amplitude of the first signal and the amplitude ofthe second signal.

The electric toothbrush shown is something wherein the correction moduleperforms corrections in the first case wherein the variation amount ofthe amplitude of the first signal is at the third threshold or more andwhen variation amount of the amplitude of the second signal is at thefourth threshold or less, or in the second case wherein the variationamount of the amplitude of the first signal is less than the thirdthreshold and the amplitude of the second signal exceeds the fourththreshold.

The electric toothbrush shown is something wherein the correction modulesubstitutes the brushing site estimated by the brushing site estimationmodule to the neighboring site in the first case.

The electric toothbrush shown is something wherein the correction modulesubstitutes the brushing site estimated by the brushing site estimationmodule to the brushing site estimated by the brushing site estimationmodule in a state just before the variation amount of the amplitude ofthe first signal becomes less than the third threshold.

The brushing site estimation method shown is a brushing site estimationmethod by an electric toothbrush having a driving module that oscillatesthe brush unit and an acceleration sensor, and is provided with a signalextraction step that extracts the first signal achieved from thefrequency of the first threshold or more and the second signal achievedfrom the frequency of the second threshold or less, a brushing siteestimation step that estimates the brushing site by the brush unit basedon the output signals of the acceleration sensor, and a correction stepthat corrects the brushing site estimated by the brushing siteestimation step.

The present invention has especially high convenience applied as ahousehold use electric toothbrush and is effective.

While the inventions have been described with respect to specificexamples, those skilled in the art will appreciate that there arenumerous variations and permutations of the above described inventions.It is to be understood that other embodiments may be utilized andstructural and functional modifications may be made without departingfrom the scope of the present inventions. Thus, the spirit and scopeshould be construed broadly as set forth in the appended claims.

What is claimed is:
 1. An electric toothbrush comprising: a drivingmodule configured to oscillate a brush unit; an acceleration sensorconfigured to generate an output signal; a signal extraction moduleconfigured to extract from the output signal (a) a first signal having afrequency at a first threshold or higher and (b) a second signal havinga frequency at a second threshold or lower; a brushing site estimationmodule configured to estimate a brushing site of the brush unit based onthe output signal of the acceleration sensor; and a correction moduleconfigured to correct the brushing site estimated by the brushing siteestimation module based on an amplitude of the first signal and anamplitude of the second signal.
 2. The electric toothbrush according toclaim 1 wherein the correction of the brushing site occurs: in a firstcase, when a variation amount of the amplitude of the first signal is ata third threshold or more, and the amplitude of the second signal is ata fourth threshold or less; or in a second case, when a variation amountof the amplitude of the first signal is less than a third threshold, andthe amplitude of the second signal exceeds a fourth threshold.
 3. Theelectric toothbrush according to claim 2 wherein, in the first case, thecorrection module substitutes the brushing site estimated by thebrushing site estimation module with a neighboring site.
 4. The electrictoothbrush according to claim 2, wherein the correction modulesubstitutes the brushing site estimated by the brushing site estimationmodule with the brushing site estimated by the brushing site estimationmodule in a state just before the variation amount of the amplitude ofthe first signal became less than the third threshold.
 5. The electronictoothbrush device according to claim 1 wherein the estimated brushingsite is one of a maxillary front buccal surface, a maxillary frontlingual surface, a maxillary left buccal surface, a maxillary leftlingual surface, a maxillary left occlusal surface, a maxillary rightbuccal surface, a maxillary right lingual surface, a maxillary rightocclusal surface, a mandibular front buccal surface, a mandibular frontlingual surface, a mandibular left buccal surface, a mandibular leftlingual surface, a mandibular left occlusal surface, a mandibular rightbuccal surface, a mandibular right lingual surface, and a mandibularocclusal surface.
 6. A brushing site estimation method for an electrictoothbrush, the method comprising: providing an electric toothbrushhaving a brush unit configured to move, an acceleration sensor, and abrushing site estimation module; extracting a first signal from anoutput signal of the acceleration sensor of an electric toothbrush, thefirst signal having a frequency at a first threshold or higher;extracting a second signal from the output signal of the accelerationsensor, the second signal having a frequency at a second threshold orlower; estimating a brushing site of the brush unit based on the outputsignal of the acceleration sensor; and correcting the brushing siteestimated by the brushing site estimation module based on an amplitudeof the first signal and an amplitude of the second signal.
 7. The methodaccording to claim 6 wherein the step of correcting the brushing siteoccurs: in a first case, when a variation amount of the amplitude of thefirst signal is at a third threshold or more, and the amplitude of thesecond signal is at a fourth threshold or less; or in a second case,when a variation amount of the amplitude of the first signal is lessthan a third threshold, and the amplitude of the second signal exceeds afourth threshold.
 8. The method according to claim 7 wherein, in thefirst case, the step of correcting the brushing site comprisessubstituting the brushing site estimated with a neighboring site.
 9. Themethod according to claim 7 wherein the step of correcting the brushingsite comprising substituting the brushing site estimated by the brushingsite estimation module with the brushing site estimated by the brushingsite estimation module in a state just before the variation amount ofthe amplitude of the first signal became less than the third threshold.10. The method according to claim 6 wherein the estimated brushing siteis one of a maxillary front buccal surface, a maxillary front lingualsurface, a maxillary left buccal surface, a maxillary left lingualsurface, a maxillary left occlusal surface, a maxillary right buccalsurface, a maxillary right lingual surface, a maxillary right occlusalsurface, a mandibular front buccal surface, a mandibular front lingualsurface, a mandibular left buccal surface, a mandibular left lingualsurface, a mandibular left occlusal surface, a mandibular right buccalsurface, a mandibular right lingual surface, and a mandibular occlusalsurface.
 11. A non-transitory computer-readable storage medium encodedwith instructions which, when executed on a processor, perform a methodof: extracting a first signal from an output signal of an accelerationsensor of an electric toothbrush, the first signal having a frequency ata first threshold or higher; extracting a second signal from the outputsignal of the acceleration sensor, the second signal having a frequencyat a second threshold or lower; estimating a brushing site of a brushunit based on the output signal of the acceleration sensor via abrushing site estimation module; and correcting the brushing siteestimated by the brushing site estimation module based on an amplitudeof the first signal and an amplitude of the second signal.
 12. Thestorage medium according to claim 11 wherein the step of correcting thebrushing site occurs: in a first case, when a variation amount of theamplitude of the first signal is at a third threshold or more, and theamplitude of the second signal is at a fourth threshold or less; or in asecond case, when a variation amount of the amplitude of the firstsignal is less than a third threshold, and the amplitude of the secondsignal exceeds a fourth threshold.
 13. The storage medium according toclaim 12 wherein, in the first case, the step of correcting the brushingsite comprises substituting the brushing site estimated with aneighboring site.
 14. The storage medium according to claim 11 whereinthe step of correcting the brushing site comprising substituting thebrushing site estimated by the brushing site estimation module with thebrushing site estimated by the brushing site estimation module in astate just before the variation amount of the amplitude of the firstsignal became less than the third threshold.
 15. The storage mediumaccording to claim 11 wherein the estimated brushing site is one of amaxillary front buccal surface, a maxillary front lingual surface, amaxillary left buccal surface, a maxillary left lingual surface, amaxillary left occlusal surface, a maxillary right buccal surface, amaxillary right lingual surface, a maxillary right occlusal surface, amandibular front buccal surface, a mandibular front lingual surface, amandibular left buccal surface, a mandibular left lingual surface, amandibular left occlusal surface, a mandibular right buccal surface, amandibular right lingual surface, and a mandibular occlusal surface.